Validate Typed operations and subqueries

[armanbilge]

GraphQLOperation.Typed and GraphQLSubquery.Typed are now pre-processed through the same codegen pipeline as their non-Typed counterparts and thus fully validated against the schema. However no modifications are applied in this case, since everything is already defined on the Typed superclass.

[rpiaggio]

Thank you for implementing this, looks awesome! Just a couple of comments:

• A query of subquery may have everything defined but not extend .Typed. Should we handle these cases?
• Is it worthwhile to add an intentionally failing test?

[armanbilge]

• A query of subquery may have everything defined but not extend .Typed. Should we handle these cases?

Oh right, I see what you mean. So we offer a general validator, independently of whether code-generation is performed or not. That seems like a good idea.

• Is it worthwhile to add an intentionally failing test?

Yeah, seems like a good idea :) at the moment we only know it exercises the codepath because the annotation is removed. I'll check how to do this with scalafix.